Changes

Depositional environment affects sediment composition by determining the amount of reworking and [[Core_description#Maturity|sorting]] by size or hydraulic equivalence. Sediments that have a higher degree of reworking are more mechanically and chemically stable. The energy level of depositional environments affects sorting by size or hydraulic equivalence and consequently produces different detrital mineral suites.<ref name=Stonecipher&May1990>Stonecipher, S. A., and J. A. May, 1990, [http://archives.datapages.com/data/specpubs/resmi1/data/a065/a065/0001/0000/0025.htm Facies controls on early diagenesis: Wilcox Group, Texas Gulf Coast], in D. Meshri and P. J. Ortoleva, eds., Prediction of Reservoir Quality Through Chemical Modeling, I: AAPG Memoir 49, p. 25–44.</ref>

Depositional environment affects sediment composition by determining the amount of reworking and [[Core_description#Maturity|sorting]] by size or hydraulic equivalence. Sediments that have a higher degree of reworking are more mechanically and chemically stable. The energy level of depositional environments affects sorting by size or hydraulic equivalence and consequently produces different detrital mineral suites.<ref name=Stonecipher&May1990>Stonecipher, S. A., and J. A. May, 1990, [http://archives.datapages.com/data/specpubs/resmi1/data/a065/a065/0001/0000/0025.htm Facies controls on early diagenesis: Wilcox Group, Texas Gulf Coast], in D. Meshri and P. J. Ortoleva, eds., Prediction of Reservoir Quality Through Chemical Modeling, I: AAPG Memoir 49, p. 25–44.</ref>

For example, different facies of the Wilcox Group along the Gulf Coast of Texas have different compositions that are independent of their source area.<ref name=Stonecipher&May1990 /> Wilcox basal fluvial point bar sands are the coarsest and contain the highest proportion of nondisaggregated lithic fragments. Prodelta sands, deposited in a more distal setting, contain fine quartz, micas, and detrital clays that are products of disaggregation. Reworked sands, such as shoreline or tidal sands, are more quartzose.

For example, different facies of the Wilcox Group along the Gulf Coast of Texas have different compositions that are independent of their source area.<ref name=Stonecipher&May1990 /> Wilcox basal fluvial point bar sands are the coarsest and contain the highest proportion of nondisaggregated lithic fragments. Prodelta sands, deposited in a more distal setting, contain fine [[quartz]], micas, and detrital clays that are products of disaggregation. Reworked sands, such as shoreline or tidal sands, are more quartzose.

==Depositional pore-water chemistry==

==Depositional pore-water chemistry==

[[file:predicting-reservoir-system-quality-and-performance_fig9-52.png|300px|thumb|{{figure number|2}} Typical diagenetic pathways for marine sediments. Copyright: Burley et al.;<ref name=ch09r7 /> courtesy Blackwell Scientific.]]

[[file:predicting-reservoir-system-quality-and-performance_fig9-52.png|300px|thumb|{{figure number|2}} Typical diagenetic pathways for marine sediments. Copyright: Burley et al.;<ref name=ch09r7 /> courtesy Blackwell Scientific.]]

The precipitation of cements in quartzarenites and subarkoses deposited in a marine environment tends to follow a predictable pattern beginning with clay authigenesis associated with quartz and feldspar overgrowths, followed by carbonate precipitation. Clay minerals form first because they precipitate more easily than quartz and feldspar overgrowths, which require more ordered crystal growth. Carbonate cement stops the further diagenesis of aluminosilicate minerals.

The precipitation of cements in quartzarenites and subarkoses deposited in a marine environment tends to follow a predictable pattern beginning with clay authigenesis associated with [[quartz]] and feldspar overgrowths, followed by carbonate precipitation. Clay minerals form first because they precipitate more easily than quartz and feldspar overgrowths, which require more ordered crystal growth. Carbonate cement stops the further diagenesis of aluminosilicate minerals.

The diagram in [[:file:predicting-reservoir-system-quality-and-performance_fig9-52.png|Figure 2]] summarizes typical diagenetic pathways for marine sediments.

The diagram in [[:file:predicting-reservoir-system-quality-and-performance_fig9-52.png|Figure 2]] summarizes typical diagenetic pathways for marine sediments.

| rowspan="2" | Eolian

| rowspan="2" | Eolian

| Dune

| Dune

| Quartz overgrowths dominate; also clay coats

| [[Quartz]] overgrowths dominate; also clay coats

|-

|-

| Interdune

| Interdune